Patent Literature 1 discloses a heat pump cycle and a defrosting control of an evaporator. Patent Literatures 2 to 5 disclose heat exchangers that allow multiple media to flow.
In a technique of Patent Literature 1, the defrosting is executed with the use of a waste heat of an internal combustion engine. However, in recent years, the waste heat of the internal combustion engine has a tendency to decrease. For that reason, there is a risk that a sufficient amount of heat is not obtained for defrosting. Also, in electric vehicles such as hybrid vehicles or electric automobiles, not only the waste heat of the internal combustion engine may be small, but also the waste heat from electric devices such as an electric motor may be also small. For that reason, there is a risk that the sufficient amount of heat is not obtained for the defrosting.
Also, in view of another aspect, the technique of Patent Literature 1 may not pay sufficient attention to that the more necessity of the defrosting, the more suppression of adhesion and growth of frost before the adhesion of frost, in other words, Patent Literature 1 may not pay sufficient attention to the suppression of frost formation. Therefore, an improvement may be required in a stage where frost formation is suppressed.
The heat exchangers disclosed in Patent Literatures 2 to 5 can be used for the defrosting. However, Patent Literatures 2 to 5 each disclose a structure of the heat exchanger, but may not conduct defrosting with the use of an appropriate heat source for defrosting.